Rolling process is most common industrial process used for making large length cross section like sheets and plates of steel and aluminum for structure and other works. Rolling mills are used to perform rolling process. These machines are available in different shapes and size according to requirement of the process and due to technical issues. Every rolling mill consist minimum two rolls. These numbers can extend according to the process requirement. Today we will discuss about all types of rolling mills used in manufacturing industries.
Types of rolling mills:
According to the number and arrangement of rolls, this machine can be classified into following types.
Two High Rolling Mill:
This mill consist two rollers arranged as shown in figure. Both the rollers rotate in opposite direction for desire movement of work piece. Work piece is feed between the rollers which apply a compressive force and tends to plastically deform work piece and convert it into desire shape.
This machine can further classified into two types. The first one is two high non reversible machine in which the rollers can rotate in only one direction (Either clockwise or anticlockwise) and thus work piece can feed only in one direction (Either left to right or right to left). One big problem arises in this machine is that every time the work piece carried back over the front side of mill to feed again for reduction in thickness.
The other one is two high reversible machine in which both the rollers can be rotate in both directions. In this machine no need to carry work piece at front side. We have to just change the direction of rotation of rollers to again pass the work piece through rollers for decrease thickness.
Three High Rolling Mill:
This type of rolling mill consist three rollers arrange parallel to each other. In this machine the middle roller rotate in opposite direction of other two rollers. This machine is used to reduce two times thickness in one pass. In this machine, the work piece is feed between bottom and middle roller in one direction and top and middle rollers in opposite direction. This machine can handle two work pieces in single run.
Four High Rolling Mill:
These machine consist four rollers (two small and two big). These rollers are arranged as shown in figure. Small rollers are in direct contact with work piece and rotate in opposite direction. Big rollers works as backup rolls and they also rotates in opposite direction with each other and also with contact roller. This machine is used for cold rolling where high rigidity required.
Tandem Rolling Mill:
Tandem rolling is also known as continuous rolling in which two or more set of four high rolling mill arranged in a series in which each set is called stand. These stands are arranged so they can roll the work piece in decreasing cross section. It is used for rolling thick work piece in single pass.
Cluster Rolling Mill:
In this type of rolling mill, each of working roller is backup by two or more of larger backup roller. These rollers are arrange as shown in figure. This machine is used for rolling hard material.
Planetary Rolling Mill:
In this type of rolling machine, a large backup roller is surrounded by various numbers of planetary working rollers as shown in figure. Each planetary roll gives constant reduction. It is used to reduce large thickness in single pass of steel strip. Its rolling capacity is more than cluster machine but less than tandem rolling machine.
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